Maximian Antoninianus. 289-290 AD. 

Obv: IMP C M A VAL MAXIMIANVS P F AVG, radiate & cuirassed bust right
Rev: CONSERVATOR AVGG, Emperor, holding sceptre, and Hercules, leaning on club, standing face to face, sacrificing at altar. A dot XXI dot HP in ex. 

This mintmark is unlisted in RIC. RIC V Siscia, 580, rated scarce.

Used with permission of TimeLine Originals (www.time-lines.co.uk), June 2009